An intake device for a vehicle utilizes the effects of intake inertia, intake pulsation, and intake resonance to improve the volumetric efficiency of intake air. The intake device can include a variable intake pipe length device capable of varying the length of an intake pipe to obtain the above effects in a wide range of engine speeds.
Conventionally known is a vehicle including a variable intake pipe length device such that a plurality of movable funnels for a plurality of cylinders are connected and driven by a single actuator and a link mechanism (see Japanese Patent Laid-open No. 2007-218243, for example).
In Japanese Patent Laid-open No. 2007-218243, a throttle body is connected to a cylinder head of an engine, and a cleaner box is connected to the throttle body.
The cleaner box contains a fixed funnel connected to the throttle body, a movable funnel adapted to be connected to or separated from the fixed funnel, and a funnel moving mechanism for moving the movable funnel. A motor as a drive source for the funnel moving mechanism is provided so as to project out of the cleaner box.
The funnel moving mechanism includes a support column mounted on the fixed funnel, a parallel link pivotably mounted through two pivot shafts to the support column, a moving member and moving shaft connected to the parallel link, and a rotation lever connected to the moving shaft and mounted on an output shaft of the motor.
When the output shaft of the motor is rotated, the moving member and the moving shaft are moved to swing the parallel link about the two pivot shafts. As a result, the movable funnel is connected to the fixed funnel to obtain a long intake pipe length corresponding to a low engine speed. Conversely, the movable funnel is separated from the fixed funnel to obtain a short intake pipe length corresponding to a high engine speed.
The funnel moving mechanism having the parallel link connects the movable funnels for the four cylinders and it is composed of many parts, causing a large size and largely projecting before the movable funnels.
Further, the number of parts of the funnel moving mechanism for moving the movable funnels is large.